Conventional power distribution system is radial in nature, characterized by a single source feeding a network of downstream feeders. Protection scheme for distribution system, primarily consisting of fuses and reclosers and, in some cases, relays, has traditionally been designed assuming the system to be radial. After connecting distributed generation (DG), part of the system may no longer be radial, which means the coordination might not hold. The effect of DG on coordination will depend on size, type, and placement of DG. This paper explores the effect of high DG penetration on protective device coordination and suggests an adaptive protection scheme as a solution to the problems identified. Results of implementation of this scheme on a simulated actual distribution feeder are reported.

Development of adaptive protection scheme for distribution systems with high penetration of distributed generation

Many methods for fault location using synchronized phasor measurement have been reported in literature. Most of these methods use voltage and current measurements at one or both ends of a transmission line. Accuracy of current measurement is limited by the accuracy of the current transformers (CT) used. This paper describes a fault-location method for transmission lines using only synchronized voltage measurements at both ends of the line, eliminating the inherent error due to CT. The method can be applied to transposed and untransposed lines. The method is tested using results from a steady state fault-analysis program and EMTP.

Fault location on a transmission line using synchronized Voltage measurements

This paper describes a new scheme to locate a fault on a multi-terminal transmission line. It describes a simple new algorithm to identify the faulted section first. Then, to exactly locate the fault on this section, a method is described that uses the synchronized voltage measurements at all terminals. The main advantage of this method is that the current-transformer errors in the current measurements can be avoided. Since these errors can be as high as 10%, the fault location is extremely accurate with this method. The scheme can work for transposed as well as untransposed lines and is free of prefault conditions. The paper, after describing the scheme, describes very promising results from an Electromagnetic Transients Program simulation of a multi-terminal transmission line.

Fault location scheme for a multi-terminal transmission line using synchronized Voltage measurements

This paper presents a critical review on different application of Phasor Measurement Units (PMUs) in electric power system
networks incorporated with FACTS controllers for advanced power system monitoring, protection, and control. Also this paper
presents the current status of the research and developments in the field of the applications of PMUs in electric power system
networks incorporated with FACTS controllers. Authors strongly believe that this survey article will be very much useful to the
researchers for finding out the relevant references in the field of the applications of PMUs in electric power system networks
incorporated with FACTS controllers.

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Applications of phasor measurement units (PMUs) in electric power system networks incorporated with FACTS controllers

This paper presents a general fault-location method for large transmission networks which uses phasor measurement unit (PMU) voltage measurements where the injected current at a fault point can be calculated by using the voltage change and its relevant transfer impedance on any bus. A two-stage fault-location optimization model is proposed, along with defining a matching degree index. The first stage is the fault region identification stage, which uses the matching degree index to determine the suspicious fault region in order to reduce the search area. The second stage is used to identify the exact fault line and fault distance. A method to determine optimal PMU placement is also proposed in this paper. Case studies verify that the proposed fault-location algorithm and optimal PMU placement scheme can locate faults in large transmission networks quickly and accurately without requiring fault-type classification or fault phase selection.

PMU-Based Fault Location Using Voltage Measurements in Large Transmission Networks

Conventional fault location systems which use one-terminal AC voltages and currents are difficult to apply to multi-terminal power systems. This paper discusses a new fault location system for multi-terminal single transmission lines. Asynchronous sampling at each terminal is preferred in order to simplify the transmission equipment and an algorithm for synchronizing the asynchronous sampling data is presented. Another algorithm is presented which converts the original multi-terminal power system by progressive conversion to a system with one fewer terminals to arrive at a 2-terminal system containing the fault. An effective fault locating system can be constructed by combining these algorithms with existing reactive power locating operations. EMTP simulation results are presented. >

Development of a new fault location system for multi-terminal single transmission lines

Conventional fault location systems which use one-terminal ac voltages and currents are difficult to apply to multi-terminal systems. This paper discusses a new fault location system for multi-terminal single transmission lines. Asynchronous sampling at each terminal is preferred in order to simplify the transmission equipment and an algorithm for synchronizing the asynchronous sampling data is presented. Another algorithm is presented which converts the original multi-terminal system by progressively conversion to a system with one fewer terminals to arrive at a 2-terminal system containing the fault. An effective fault locating system can be constructed by combining these algorithms with existing reactive power locating operations.EMTP simulation results are presented.

T. Emura

Papers

Development of a new fault location system for multi-terminal single transmission lines

Development of a new fault location system for multi-terminal single transmission lines